Build Your Own Clone Message Board

This goes out to all the Stutter Trem builders (and/or Nathan/CJ):

I built both of my two Stutter Trems with the stock values, using the Shunt layout. (also employed the latching momentary stomp on both).

When setting the Rate to max speed (or near max), the LFO dies out and I get no trem. Sometimes backing the rate down doesn't seem to fix it, and I end up disconnecting the power and plugging it back in to 'reset' it. Kind of a pain.. anyone else experience this? Simple fix?

This is definitely a question for Nathan (FF_Pedals). He's the Master's EE around here. Literally.

Whoops, I had Rick on the brain.. posted edited, sorry Nathan

That's annoying. So stock you used 1uF caps in the LFO? I'll look into it .

yep, C9, 10, 11- 1uf..

Here's my latest Stutter build, it won't help you any, but if you haven't seen it..
http://www.buildyourownclone.com/board/viewtopic.php?f=8&t=36914

That does help, I was going to ask what kind of LED you used in the LFO . I used green diffused too. Hmm. I used 4k7 for R20 instead of 15k, it gives a little bit more speed on the rate. I just pulled my build out to play it a bit and test it, I don't seem to have that problem. How long does it take for the LFO to die out? Does it depend on the duty cycle control?

I really don't know what this has to do with helping Eric but I guess it's all good

I have the same problem with mine as well only it dies out when the rate is at max and min.

Do you guys have other transistors around that would be from the same batch that you could measure the hfe on? For the 2N5088 and 2N3904.

You think you're funny!

Unfortunately not I just bought another board from CJ so hopefully the next one will work.

hmm, this is interesting: I measured some 5088's from my stash, and they are hovering in the 425 to 450hfe range. One oddball coming in at 591.

But with the 3904, I have two brands mixed together, one with straight pins and one with pre-bent wide pins. One ranges between 320-340hfe, and the other ranges between 150-190hfe.

will need to inspect what's in the pedal to see which 3904 brand might be in there.

Glad I bought that Peak transistor tester though!

Hell yeah!

Hey, don't make me use that as my new sig

Wow, is this wide of a swing that normal? I mean that is huge right?

In my SPICE model I used a 2N5088 model that I think has hfe = 750. They usually are way over optimistic. The 2N3904 had something like 400 which is really high. I have another model for 2N3904 with hfe around 190 and the ones I used are around that. I'll test one of my 5088 from my parts pile.

@Powerpop guy I'm no EE (AND I've never built this pedal ) but I have an idea.

I am assuming that you turn the rate knob all the way to the right to increase the rate. What if you soldered a high value resistor between pins one and two on the pot?

Yeah, that could help, but I'm really more curious about the issue itself than I am about the solution at this point. Also, I think KBC is right, the trem may have died out on me at minimum setting too. I have to fire it up again tonight to be sure about that.

I'm also frustrated with these pesky 2n3904's with crazy gain variances. I expected more standardized gain ranges out of silicon transistors

Hey Eric / other guys building the stutter.

I'm leaning towards it being a problem with certain brands of electrolytic capacitors.

The way the oscillator works is it's a voltage amplifier with a 3rd order RC high pass filter from the output to input of the amplifier. There's a phase shift in this RC filter. Depending on the value of the capacitors and resistors there's a 180 degree phase shift at a certain frequency in the filter network and that provides the condition for oscillation. I can post some more notes on this later if anyone's interested.

In the electrolytic capacitors there are parasitics that can change the function of the filter. I tested my build with electrolytics and it works fine but not all brands are the same.

I noticed the BYOC EA trem ships with film capacitors and the original Electronics Australia article says not to use electrolytic capacitors.

I'd try using multilayer ceramic caps since you can get them nice and small with a 2.5mm lead spacing that will fit on the stutter trem board. Ceramic capacitors are used for filters and timing circuits.

Here are some at Mouser you might consider: http://ca.mouser.com/ProductDetail/TDK/ ... ZjKaQDM%3d

I'll look to see if I have any, I don't think I do, otherwise I'd send some for you to test it out.

Tayda has 1uF mono ceramics:
http://www.taydaelectronics.com/capacit ... citor.html

I had some 1uf tants so I replaced C9, C10, and C11 with them and it now works great at full speed. It still dies out and ends up just straight guitar and no trem when the rate is at min, but it might have something to do with the wah pot I'm using that measures over 130k when it's only supposed to be 100k.

Cool, thanks for the update.

I guess you aren't getting the 180 degree phase shift in the filter when you're at 130k on your wah pot.

ok, I guess I'll take a crack at replacing those caps (I think I may have some tants or multilayer 1ufs around). My wiring is pretty short, but I'll see if I can get at the underside of the board. I do have the the proper pot values, so it should be a good experiment.

What pot values did you use?